On Friday, if someone had told you that Argentina would struggle to score a goal against Iran on Saturday, or that Germany would draw 2-2 against Ghana on the same day, you might have called that person crazy.

But that was the tense reality of the World Cup on day 10 of the event in Brazil. Only after a legendary goal in the final minutes of the match by Lionel Messi did Argentina find a victory. It was also a victory that proved that while Messi is easily the best soccer player in the world, Argentina is going to need more than luck to make it in the knockout round.

Later, in a battle that turned out to be much less one-sided than expected, Germany (the favorite to win) and Ghana clashed, with the match ending in a draw.

With more heavyweights set to meet on Sunday, what stories will further develop in Group G and Group H? Let's look at what you should expect for Sunday's matches.

Belgium vs. Russia

Dries Mertens scores Belgium's second goal during the Group H World Cup soccer match between Belgium and Algeria at the Mineirao Stadium in Belo Horizonte, Brazil on June 17.

Image: Ricardo Mazalan/Associated Press

Belgium is largely believed to be one of the World Cup's dark horses. With a new, gifted generation of Belgian players emerging from almost 12 years of being nonexistent on the national stage, a 2010 Germany story — a youthful team showing promise and exceptional talent — could very well be in the cards for Belgium.

This game will determine an advancement out of Group H. Based solely on the teams' opening matches, Belgium should be the favored winner. Russia failed to find anything substantial in their game against the Korea Republic, whilst Belgium found the keys to a win when it mattered in the second half versus Algeria.

And in a Belgium win, you'll want to watch for two substitutes turned Belgian legends. If the domination of the CONCACAF (the Confederation of North, Central American and Caribbean Association Football) league is one emerging storyline of this World Cup, the deadly potential of the correct substitute is another.

In Belgium's match on Tuesday, substitute Marouane Fellaini came in at the 65th minute and scored the Belgian equalizer goal at 70th minute. Soon after, a spirited Belgian sub in Dries Mertens who took the pitch in the 46th minute later scored in the 80th minute for the win. So it'll be interesting to see if Belgium decides to start Mertens and Fellaini after they proved to be vast upgrades for Belgium in a comparatively lackluster first half.

Korea Republic vs. Algeria

South Korea's Lee Keun-ho, bottom, celebrates after scoring the opening goal during the Group H World Cup soccer match between Russia and South Korea at the Arena Pantanal in Cuiaba, Brazil, Tuesday on June 17.

Image: Lee Jin-man)/Associated Press

Depending on how the Belgium vs Russia game ends, the Korea Republic has a chance at advancing out of their group with a win over Algeria.

It'll be difficult though because Algeria — although ultimately losing — didn't keel over against Belgium. They showed early signs of life against Belgium, until Fellaini and Mertens came in during the second half.

With their 1 point from a 1-1 draw against Russia and a better goal differential than Algeria, the Korea Republic has the best shot at making a run for the second seed, but a shot that requires Russia — a favored winner — to lose to Algeria. But favorites in this tournament are hardly certain winners, and fans in Seoul will come out in droves to see their team make a miraculous run out of Group H — instead of a flight home.

USA vs. Portugal

And then there's the marquee match of the day.

A dejected Cristiano Ronaldo of Portugal looks on after being defeated by Germany 4-0 during the 2014 FIFA World Cup Brazil Group G match between Germany and Portugal at Arena Fonte Nova on June 16 in Salvador, Brazil.

Image: Phil Walter/Getty Images

Group G was supposed to be Team USA's "Group of Death," but with the exception of Germany, they've shown the most life.

So who do we watch out for? Naturally, Portugal's success weighs largely on Cristiano Ronaldo's shoulders — carrying his team out of group stages, like he carried them through the World Cup qualifiers. If the USA plays like they did against Ghana on Monday, it's a very real possibility that Portugal will overwhelm the U.S. squad. Lightning rarely strikes twice, and though the USA team plays with heart, you can't rely on game-changing, last minute goals — by substitute John Brooks no less — to beat Ronaldo when he's on his game.

On the opposite side of the pitch, Jozy Alitdore is out in this game against Portugal with a strained hamstring. In his absence, various members of the USMNT will be charged with insuring a win. The U.S. offense will entirely be led by Clint Dempsey, especially if midfielder Michael Bradley repeats his performance against Ghana. Bradley — often noted as controlling the pace of Team USA's offense — was just nonexistent.

That being said, USA's defense proved to be formidable. Tim Howard, as usual, is a wall and has had one of the best keeping performances in the tournament — up there with Mexico's Guillermo Ochoa. Helping Howard out will be Jermaine Jones who really showed up and was the highlight of an otherwise tired USA defense.

Lastly, let's look at the future of Group G. If USA comes out blazing and bests Portugal, they will earn a spot into the knockout round and contest first when they face Germany in their last match of the group stage.

World Cup of Hugs

United States' goalkeeper Tim Howard, left, embraces Kyle Beckerman after the Group G World Cup soccer match between Ghana and the United States at the Arena das Dunas in Natal, Brazil on June 16, 2014. The United States won the match 2-1.

Image: Ricardo Mazalan/Associated Press

Belgium's Dries Mertens, front, is embraced by Axel Witsel as he celebrates after scoring Belgium's second goal during the Group H World Cup soccer match between Belgium and Algeria at the Mineirao Stadium in Belo Horizonte, Brazil, on June 17.

Image: Hassan Ammar/Associated Press

Argentina's Lionel Messi (10) is congratulated by Bosnia's Haris Medunjanin (18) following Argentina's 2-1 victory in a Group F World Cup soccer match at the Maracana Stadium in Rio de Janeiro, Brazil on June 15.

Image: Kirsty Wigglesworth/Associated Press

Brazil's Neymar celebrates his goal in the first half with his teammates during the Group A World Cup soccer match between Brazil and Croatia, the opening game of the tournament, in the Itaquerao Stadium in Sao Paulo, Brazil on June 12.

Image: Fabrizio Bensch/Associated Press

Brazil's coach Luiz Felipe Scolari, left, hugs Mexico's head coach Miguel Herrera after the Group A World Cup soccer match between Brazil and Mexico at the Arena Castelao in Fortaleza, Brazil on June 17.

Image: Themba Hadebe/Associated Press

Ivory Coast's Serge Aurier is hugged by a team member after their 2-1 victory over Japan in a Group C World Cup soccer match at the Arena Pernambuco in Recife, Brazil on June 15.

Image: Dolores Ochoa/Associated Press

Chile's Gary Medel (17) hugs goalkeeper Claudio Bravo after Eduardo Vargas scored Chile's first goal during the Group B World Cup soccer match between Spain and Chile at the Maracana Stadium in Rio de Janeiro, Brazil on June 18.

Image: Natacha Pisarenko/Associated Press

Italy's Thiago Motta (5) hugs Andrea Pirlo (21) as Giorgio Chiellini (3) joins them after defeating England 2-1 in their Group D World Cup soccer match at the Arena da Amazonia in Manaus, Brazil on June 14.

Image: Marcio Jose Sanchez/Associated Press

Mexico's Rafael Marquez, left, embraces Mexico's goalkeeper Guillermo Ochoa after the Group A World Cup soccer match between Brazil and Mexico at the Arena Castelao in Fortaleza, Brazil on June 17. The match ended in a 0-0 draw.

Image: Martin Mejia/Associated Press

Netherlands' Arjen Robben, left, hugs Australia's Tim Cahill following Australia's 3-2 loss to the Netherlands during the Group B World Cup soccer match at the Estadio Beira-Rio in Porto Alegre, Brazil on June 18.

Image: Fernando Vergara/Associated Press

Chile's Gary Medel hugs Spain's Sergio Ramos following the Group B World Cup soccer match between Spain and Chile at the Maracana Stadium in Rio de Janeiro, Brazil on June 18. Defending champion Spain was eliminated from the World Cup after losing to Chile 2-0.

Image: Frank Augstein/Associated Press

Chile's Eduardo Vargas, center, celebrates with teammates after scoring the opening goal during the Group B World Cup soccer match between Spain and Chile at the Maracana Stadium in Rio de Janeiro, Brazil on June 18.

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